Describing sounds, smells, leaks and feel so a technician can find the problem

Write a symptom down by what, where, when and how often, describe a leak by color, place and size, know the signs that mean stop driving, and hand the shop a note it can use.

Writing a symptom down: what, where, when, how often Understand

A symptom is what you notice: a sound, a smell, a feel, a light, a leak, smoke. A cause is what a technician finds. The gap between the two is where a repair visit goes well or badly. A noise that happens only on cold mornings, or only in right turns, may not happen in the ten minutes a technician has the car, and the more precisely you describe when it happens, the better the chance they find it.

California's Bureau of Automotive Repair (BAR), the state agency that licenses repair shops there, puts the questions a technician will ask in its consumer guide: where in the car the sound comes from; when it happens, whether with the engine running, cold, accelerating, braking, turning, or above or at a certain speed; whether you feel vibration in the steering column or the brake pedal; whether the steering pulls to one side; whether the tires wear unevenly; whether fuel economy is falling; and whether you regularly add coolant or oil (California BAR, A Consumer's Guide to Auto Repair). The guide says to be as detailed as possible, not to rush, and not to let yourself be intimidated.

This manual turns those questions into six lines, which are the columns of the symptom log. This manual's convention

Two rules make the entry useful. First, write what you noticed, not what you think the cause is. "Grinding from the front left when braking" helps a technician; "bad brake pads" sends them looking for the answer you chose. Second, write it the day you notice it and add to it each time it happens, with the odometer reading. A symptom that is getting worse is information the shop needs, and so is one that has stopped.

If you can, describe a sound the way it sounds: a squeal, a squeak, a grind, a click, a tick, a knock, a clunk, a hum, a whine, a hiss, a rattle. Say whether it keeps time with the wheels (faster as the car speeds up) or with the engine (faster as you press the accelerator, even standing still). A recording of the sound helps when it does not happen on demand; the rule for making one is that the driver does not record while driving. A passenger records, or the car is parked. This manual's convention

Sounds and feel

Makers and motor clubs publish plain descriptions of what some sounds and feelings can point to. Read them for what they are: a list of things a technician will check, which helps you describe what you hear. They do not tell you the cause on your car. Convention

Brakes

Chevrolet's owner page on the brake system lists the signs a driver can notice (Chevrolet, About the brake system):

• A chirping, squealing or whistling sound from the brakes. Many brake pads have a wear indicator, a small metal tab that touches the brake rotor when the pad is getting thin and makes that sound on purpose. Some models have an electronic pad-life monitor instead.
• Grinding.
• Stops that take longer than they did.
• A spongy brake pedal, or one that goes down farther than normal.
• Vibration in the brake pedal or the steering wheel when braking.
• The car pulling left or right when braking.

Toyota Canada's page adds that grinding can mean metal-on-metal contact with the pads worn through, and that a soft or mushy pedal can mean a problem with the brake fluid or the lines (Toyota Canada, 5 warning signs). Chevrolet says there are no specific mileage intervals for brake service because wear depends on how the car is driven, which is why these signs and the shop's measurements matter more than a mileage. Brakes, battery, wipers and lights covers the measurements to ask for. Product-specific

Other sounds

AAA Western and Central New York's guide pairs a few sounds with what a mechanic will usually look at (AAA Western and Central New York, Smells and sounds that could mean car trouble):

• A squeal when accelerating: possibly the belt that drives the engine's accessories, the serpentine belt.
• A whine: possibly the power steering.
• A ticking with an exhaust smell: a possible exhaust leak, which AAA says to have looked at right away.
• Grinding or screeching when braking: likely worn pads.

Feel

A vibration, a pull, a change in how the car steers or shifts, or less power is a symptom too, and often a harder one to describe. AAA's guide suggests noting how a vibration changes and where it seems to come from, then telling the mechanic. Useful details: whether it starts at a certain speed and fades above it, whether you feel it in the steering wheel, the seat or the pedal, and whether it changes when you brake, accelerate or coast. BAR adds the slow changes: uneven tire wear, falling fuel economy, and needing to add oil or coolant between services. Each goes on the log as it is noticed. This manual's convention

Hybrids and electric cars

An electric car has no engine sound, and a hybrid's engine is often off at low speed, so a noise from the brakes, tires or suspension has less to compete with. Physical principle The same six lines apply. Two things differ. The Department of Energy says regenerative braking greatly reduces brake wear on electric cars, so the brakes do less work, and Tesla's schedule asks owners on salted roads to have the brakes cleaned and lubricated every year or 12,500 miles (Tesla, Vehicle Maintenance); that is Tesla's interval for its own cars, and your maker's schedule gives yours. Product-specific And a hybrid or electric car carries a high-voltage system, marked with orange cables, that the Department of Energy says typically runs at 400 to 1,000 volts (AFDC, Maintenance and Safety of Electric Vehicles). Describe, photograph and report; do not touch orange cables or parts. Hybrids and electric cars covers who services them.

Smells and smoke

A smell is often the first sign of a fluid where it should not be, or something hot that should not be. The table pairs the smells two sources describe with what to tell the shop. The sources are the Car Care Council, an aftermarket industry group, in a release reprinted by the Automotive Service Association's magazine (AutoInc., Your Nose Knows), and AAA Western and Central New York's guide. Convention

The catalytic converter is the part of the exhaust system that cleans the exhaust gases. Its smell is listed here because both sources list it; whether it is the converter is a question for the shop's test, as Warning lights and codes explains for any check engine light that comes with it.

Smoke and steam

Smoke or steam from under the hood, from a wheel or from the exhaust is a stop-driving line in this manual. Pull over where it is safe, turn the engine off, and leave the radiator and coolant caps closed. Kia's 2024 manual warns that hot coolant or steam can cause serious injury, and Mazda says not to open the coolant reservoir cap while the engine is hot (Kia owner's manual, checking the coolant level; Mazda, Car Dashboard Lights Explained). Note the color of the smoke and where it came from, and call. This manual's convention

Leaks: color, place and size

A spot under a parked car is the symptom that is easiest to describe well, because it stays still. Three facts make the description: the color, the place under the car, and the size. AAA Club Alliance's guide to leaks starts with the nose: if it smells like gasoline and you did not spill any at the pump, treat it as serious, do not drive the car, and call a professional mechanic (AAA Club Alliance, Identify Car Leaks Like a Pro). Otherwise it suggests dabbing the spot with a clean white paper towel to see the color and smell it, and noting where under the car it was, which you can match to the diagrams in your owner's manual.

The cardboard check

To see a leak clearly, this manual suggests a sheet of flattened cardboard or white paper under the car overnight. This manual's convention

1. Park on a level spot where you can see the ground, with the engine off and the parking brake on.
2. Slide the cardboard under the engine area, or wherever you saw the spot, from the side or front. Push it with a broom if needed. Do not crawl or reach under the car.
3. In the morning, before moving the car, mark which edge of the cardboard faced the front of the car and which side was the driver's, so the spot's place is fixed.
4. Note the color (a white paper towel shows it best), the place (front, middle or rear; left, center or right; near which wheel) and the size (a few drops, a coin, a palm, a puddle). Photograph it with a coin for scale.
5. Wash your hands after handling it.

What the colors may be

AAA's guide gives the usual colors and is clear that color alone is not enough: an amber, brown or black spot is likely engine oil, but it may be brake fluid; transmission fluid and power steering fluid are both red; coolant was traditionally green and now comes in other colors. So every row below points to what to tell a technician, not to a cause. Convention

The brake fluid reservoir is usually on the driver's side under the hood, AAA says, and the fluid runs from there to each wheel, so a brake fluid leak can show up near a wheel. Whether your manual asks owners to check the brake fluid level, and how, is in its maintenance section; Oil, fluids and filters covers the owner checks. Product-specific

When to stop driving

Some symptoms go on the log after the car is stopped, not before. This list gathers the makers' red-light instructions and the sources above into the lines this manual treats as stop and call: pull over where it is safe, turn the engine off, and call the shop or your roadside service before driving on. This manual's convention

• A red light your manual says to stop for. Oil pressure, coolant temperature, and the brake warning light with the parking brake released are the common ones; Hyundai says not to drive until low brake fluid is filled, and Chevrolet says to plan for a tow when the engine overheats (Hyundai, warning lights; Chevrolet, warning lights). Warning lights and codes lists them.
• A flashing check engine light, especially with shaking. Follow your manual's instruction for it.
• Any brake symptom: a soft or sinking pedal, grinding, a hard pull when braking, longer stops, a brake smell, a brake fluid leak, or the brake light staying on.
• Any steering symptom: steering that suddenly turns heavy, pulls hard, wanders, or makes a new noise. Volkswagen puts a steering malfunction in its red, stop group of lights.
• A fuel smell or a fuel leak. AAA says not to drive a car that is leaking gas.
• Smoke or steam from under the hood, a wheel or the exhaust.
• Exhaust smell inside the car. See carbon monoxide below.
• On a hybrid or electric car, a high-voltage warning your manual says to stop for, or damage near orange cables or parts.

A symptom that is not on this list still goes to the shop; the list says which ones not to drive on while you wait. If you are not sure whether a line applies, read it the cautious way and call. Ask the shop or your roadside service whether to drive it in or have it towed. Ask the authority

Handing it to the shop

The person you talk to at the counter is the service advisor (also called a service writer or service consultant). Their job, in the task list that ASE's certification test for advisors covers, includes discussing and documenting your concern, reviewing the car's service history, and confirming that the repair order is accurate before getting your authorization (ASE, Automobile Service Consultant (C1) study guide). The document they write is the work order or repair order: the shop's record of the car, your concern, and the work you authorize.

Technician training programs accredited by the ASE Education Foundation teach that a work order records the customer concern, the cause and the correction, which the standards call the three Cs (ASE Education Foundation, Automobile Program Standards). The concern is the line that carries your symptom. If it says "check noise," the technician starts from two words. If it says "squeal, front left, light braking under 20 mph, every stop for three days, started after the oil change," they start from your log. Convention

At the counter

• Hand over the log. Print the symptom log, show it on your phone, or read it out. Give the recording if you have one.
• Ask that the concern go on the work order in your words. Read it back before you leave. This manual's convention
• Ask what happens next. BAR's guide notes that the advisor probably cannot diagnose the problem on the spot, and suggests asking questions, asking for clarification of any answer you do not understand, and making sure the shop has a number where it can reach you and says when it will call.
• Ask for a call before any work, and before any amount over the estimate. The questions for the shop sheet carries these at drop-off, with the question about what diagnosis costs.
• If it happens only at speed or in certain conditions, say so and ask whether the technician can drive the car under those conditions, or with you. This manual's convention
• Read the work order before you sign it. BAR's guide says: do not sign a blank work order. A signature on a blank order authorizes work you have not seen. Ask the authority

In California, BAR says a shop must give a written estimate before doing any work. That is one state's rule; other states differ, and Estimate terms lists examples and how to find your own state's. What the estimate says, and what you authorize, is in Reading a repair estimate.

After the visit

When the invoice comes, copy your concern, the cause and the correction to the service log, and write the outcome on the symptom log: fixed, not found, or recheck. A symptom the shop could not reproduce stays open on the log; if it comes back, the new entry and the old one together are what the next visit needs. If the shop gives you a list of further work, Discussing recommendations covers the four questions to ask about each item.

See it: Gloria's symptom log, and a what-if for Sam See it

• California BAR, A Consumer's Guide to Auto Repair (PDF): the questions a technician asks, and the paperwork rules for California.
• AAA Club Alliance, Identify Car Leaks Like a Pro: colors, places, and why color alone is not enough.
• Chevrolet, About the brake system: the brake signs a driver can notice.
• CDC, Carbon Monoxide Poisoning Basics: why an exhaust leak matters and what CDC says about garages.

Practice: one symptom, written and handed over Practice

Minimum: one symptom on the symptom log with all six lines and a next step, the stop-driving list checked, and for a leak, one night of cardboard. Time: about 15 minutes, plus one night for a leak. Materials: the symptom log (or paper), the odometer reading, a flattened cardboard box or sheets of white paper, a white paper towel, a phone camera, and a coin for scale.

1. Check the stop-driving list. If a line applies, the car stays parked and the next step is a call.
2. Write the six lines. What, where, when, how often, since when, getting worse. Write what you noticed, not a cause.
3. For a leak, do the cardboard check. One night, then color, place and size, with a photo and a coin.
4. Write the next step. Which shop, when you will call, and the question you will ask first.
5. Hand it over. Give the log to the advisor, ask that the concern go on the work order in your words, read it back, and do not sign a blank order.

Your car Your car

Check your work Check your work

Criteria

• Does the entry say what you noticed, not what you think the cause is?
• Does it have all six lines, with the conditions under "when" specific enough that someone else could make the symptom happen?
• For a leak: are the color, the place and the size written, with a photo?
• Did you check the stop-driving list, and is the answer on the log?
• Is there a next step with a shop and a date, and did the concern go on the work order in your words?

Worked example

Gloria's entry passes: it names the light, the shaking, where she felt it, the conditions, how often, since when, that it is getting worse, and that the stop-driving line applied. It does not say "bad spark plug" or "bad coil"; it says what she saw and felt, and the cause line waits for the shop. The converter is written as open, with the recheck. Sam's what-if passes too: the six lines are there, the recording was made by a passenger, the brake symptom triggered a call before more driving, and the maintenance question is marked open with the records that settle it.

Common mistakes

• Writing the cause instead of the symptom. "Needs pads" is a conclusion; "grinding, front left, every stop" is a description a technician can use.
• Leaving out the conditions. "Makes a noise" without when, how often and at what speed gives the shop nothing to reproduce.
• Reading a fluid color as a diagnosis. AAA says an amber or brown spot may be oil or brake fluid. Report the color and the place.
• Watching a brake or steering symptom for a few more days. These are stop-and-call lines.
• Recording while driving. A passenger records, or the car is parked.
• Signing a work order with the work left blank. BAR says not to.

What is still unresolved

The cause of any symptom is settled by the shop's inspection and test, and what the repair costs by its written estimate, read with Reading a repair estimate. A warning light that comes with a symptom is read with Warning lights and codes. The brake measurements to ask for are in Brakes, battery, wipers and lights. Which of the shop's recommendations to say yes to is in Discussing recommendations, and a shop that will not take your concern seriously is a reason to read Choosing a shop and handling problems.

Knowledge check and scenario

Checklist

• The symptom log has the entry with its conditions and a next step, and the shop has it.
• I checked the stop-driving list before deciding to drive, and wrote the answer on the log.
• For a leak, I wrote the color, the place and the size from a cardboard check, with a photo.
• I asked that the concern go on the work order in my words, and read the work order before signing it.
• I made a recording safely, or copied concern, cause and correction to the service log after the visit. (Go deeper; optional)